This is the last Saint book written in toto by Leslie Charteris, subsequent efforts being ghosted under his "supervision" with increasingly dismal results (although the first such, Vendetta for Saint by Harry Harrison, is worthy of inclusion in the canon).
There are seven stories here, set in Cannes, St Tropez, England*, Nassau, Florida, Lucerne and Provence.
The later Saint books seem to feature gradually increasing gastronomic content, this topic being particularly prominent in the final story. Personally I find this unobjectionable — in fact, rather interesting, especially since Charteris seems to know much more about the subject than I do.
Simon still seems to be pulling the birds with no trouble, although by this time he must be in his early 60s; and there are in fact a few references to his advancing years, so fair enough.
(Of course, by the the time the promised new TV series produced by Roger Moore comes out, he'll be a centenarian.)
*Yes, really. Opening sentence: "Contrary to the belief of many inhabitants of less rugged climes, the sun really does sometimes shine in England, though it is admittedly a fickle phenomenon which imparts a strong element of gambling to planning any outdoor activity".
P.S. For a list of — and discussion of — all Charteris's Saint books, see my So You'd Like To... Guide.